More winter on the way: System in place to bring wintry mess

The National Weather Service has upgraded Sunday’s forecast to a Winter Storm Warning, in effect from midnight Monday through 6 p.m. Monday evening.

The storm is expected to start later on Sunday with freezing rain, then sleet, before changing to heavy snow overnight. According to ABC 7/WTOP Weather Center, the latest rate of precipitation is 5 to 10 inches. There’s a good possibility that some spots will see more than 8 inches of snow.

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The Winter Storm Warning is for the entire area from 7 p.m. Sunday through 6 p.m. Monday.

UPDATE: Sunday March 2, 2014 3:30 a.m.

The National Weather Service has upgraded Sunday’s forecast to a Winter Storm Warning, in effect from midnight Monday through 6 p.m. Monday evening.

Precipitation is expected to start later on Sunday with freezing rain, then sleet, before changing to heavy snow overnight, with 8 to 12 inches (6 to 10 inches in the outer-suburbs) expected in the Greater D.C. Metro area.

UPDATE: Saturday March 1, 2014 9:30 p.m.

A Winter Storm Watch remains in effect for the WTOP listening area from late Sunday night through Monday afternoon.

According to the latest from the National Weather Service, precipitation will begin later on Sunday with freezing rain and sleet, then changing to snow sometime overnight, with a potential for five or more inches of snow and sleet and possibly some ice accumulation from the freezing rain.

Temperatures are expected to be in the lower 30’s overnight Sunday, then getting cold — down to the lower 20’s for Monday.

UPDATE: Saturday March 1, 2014 12:00 p.m.

While it is STILL not certain where the heaviest snow and ice will around the region, we do know that there is a good possibility of seeing both overnight Sunday and through the day on Monday. The National Weather Service has now placed the listening area in a Winter Storm Watch, so be prepared for an upgrade to a Winter Storm Warning as we head into Sunday.

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Winter Storm Watch for the region from Sunday evening until Monday afternoon

What we know: Sunday is going to be a very mild day! The closer to the Mason Dixon line you live, the better the chance of seeing temperatures in the 40s. The closer you are to Central Virginia, the better chance you have of seeing temperatures in the lower 60s. D.C. will fall somewhere in the middle for daytime highs, which will still be fairly warm-50s. Sunday evening is still looking like the start time for rain to move into the region. The rain/snow line will creep down from the north to the south during Sunday night.

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Timeline of what to expect across our region

The transition from rain to snow will be a wintry mix, most likely sleet but there will also be pockets of freezing rain. Unfortunately, depending on how quick the column of air can cool will depend on just how long the wintry mix will hold on which will mean more in the way of ice accumulation. The graphic below shows where the rain/snow line could be by 11PM on Sunday night. It is fairly close to the D.C. metro area. This is something we will continue to watch-how quickly can we get cold air into the region for a change from rain to mix to snow. This is still a question to be determined but coming into better clarity. This is why it is just impossible at this time to accurately forecast snow totals/ice totals but again, there will most likely be significant amounts of both.

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Our in-house model showing the possibility of rain (green), mix (pink) and snow (blue) by 11p.m. on Sunday. We will have to continue to watch how quickly cold air is drawn into the system.

Post dawn hours on Monday, it looks like snow for most of the region. That snow will continue, bringing down some significant accumulations. Again, it is too early to draw on a map to see who is going to get the most snow or what locations are going to receive the most ice but that is something we will nail down by tonight. Just understand that if you are in the D.C. region, you are going to most likely see a highly impactful winter storm Monday.

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I debated on throwing this in the blog but this is JUST a simulation from the National Weather Service that was run on Friday afternoon. Take this with a grain of salt but I DO want to point out some of the things we are looking over to try to put this puzzle piece together. Obviously a lot can change as the system continues to form but this is just one glance of meteorologist’s predicament- who is going to get what and how much? Just know it has the potential to be a highly impactful event. More updates to come but winter continues.

UPDATE: Saturday March 1, 2014 8:00 a.m.

A winter storm watch has been posted for the entire listening area from Sunday evening until Monday afternoon. Accumulating snow and sleet are possible.

UPDATE: Saturday March 1, 2014 3:45 a.m.

The National Weather Service has issued a Winter Storm Watch in effect for Sunday evening through Monday afternoon. The advisory forecasts freezing rain, sleet and snow, with potential accumulation of five or more inches of snow.

Freezing rain is expected to begin Sunday evening, changing to snow — heavy at times — overnight, through Monday. Hazardous travel conditions are a real possibility with icy, then snow roads for Monday.

Temperatures are expected to be in the lower 30’s Sunday evening, dropping to the mid-20’s through Monday. Winds are expected at five to 15 miles per hour, with gusts upwards of 25 miles per hour.

UPDATE: Friday Feb. 28, 2014 5:40 p.m.

Temperature data is still coming in for Sunday and there will be a HUGE difference in daytime highs on Sunday which will make forecasting Sunday’s event that much more difficult. Temperatures in the D.C. region could very well reach 50 degrees with colder air to the north (temperatures staying in the 40s) and with even warmer air to the south (some locations approaching 60 degrees).

The precip will begin most likely after dinnertime on Sunday so if you have things to get done during the day on Sunday, you will be fine. However, after the dinner rush, all bets are off.

Precip type is always a challenge. Sometimes I wish we were just cold enough where the precip type would be snow and then we could simply concentrate on totals. But now comes the difficult part.

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This is not a forecast — just a scenario discussing the difficulty predicting precip types through different layers in the atmospheres and temperature profiles in those layers at different locations.

During this Friday night update, it’s looking to start off as rain across the region. Temperatures will slowly creep toward the freezing mark from the north to the south through the late evening hours and as this happens, we’ll see the change to a different precip. Well above the surface, the atmosphere still looks to be above freezing. Therefore sleet (with some pockets of freezing rain to the south) is looking like more of a possibility as we go into the pre-dawn hours on Monday for some of our listening area, moving from the north to the south.

Eventually, the column of cold air will cool and snow will begin to fall through the post dawn hours and continuing through the day on Monday. We are still anticipating an exit of the system by Monday night.

If you’re traveling at any time during the Sunday and Monday timeframe you really want to keep your eyes on the forecast. This system is not only affecting our region but will also wreak havoc on the Midwest as the energy pushes off the west coast and travels eastward. Winter storm watches are already in place across the mid portion of the United States.

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Again, it’s way too early to push out snow totals or ice accumulation maps as we still have plenty of time for the event. I’m just telling you what we know tonight and what the current thinking is at this time. We will continue to analyze the information as it comes in but of course, as we get closer to the event our confidence gets higher.

EARLIER: Friday Feb. 28, 2014 at 1:05 p.m.

WASHINGTON — What has felt like a long winter is about to get even longer as another winter storm system takes aim at the D.C. area.

A storm system is still set to hit the region Monday, just to make Mondays that much worse. While not too much is known about the storm, one thing we do know is that this storm has all the necessary ingredients to drop another wintry mess throughout the area.

It is known that the D.C. region will see some sort of precipitation on Monday.

I apologize for the vagueness, but that is just the way it is at this point.

Be aware that there could be some social media outlets that have claimed to have nailed down specifics of this storm, but that’s not quite possible yet, unfortunately. It is still too early to tell as models continue to be in a great deal of disagreement (per usual it seems this year) about what exactly we could see here in the region.

As always, it depends on the track of a storm to determine precipitation types and we just do not know that yet.

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A storm off the Pacific Coast Friday will head to the D.C. area for Sunday night into Monday.

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The progression of the front through the Mid-Atlantic 7 a.m. Saturday through 7 a.m. Tuesday.

The storm system is moving over the West Coast of the United States bringing much-needed rain to California and much-needed snow to the mountainous regions.

That energy entering California will eventually move east toward the east coast by Sunday evening. A frontal boundary will move into the eastern U.S. and pretty much stall across the region this weekend, extending into the D.C. region. An area of low pressure will develop across the southern plains along the front.

It is this frontal boundary that will act as a roadway, bringing precipitation right into the D.C. region from the Mid West for Sunday night into Monday night timeframe.

As cold arctic air will be spilling in from the north, moisture will lift over the front from the south and interact with the cold air to the north. This will result in precipitation, some of it of the winter nature.

It is really going to depend on where this front sets up (because that will dictate temperatures) to determine precipitation type around the region and when it will fall.

At this point, it does look like the Monday morning commute could be disrupted in spots, but again, where those spots are located is still left to be determined as we try to pinpoint the location of the rain/snow line and where the heaviest precipitation will be positioned.

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With mild air to the South of the stalled cold front and cold air to the North, precipitation type, amount and timing will be difficult to determine at this time.

One thing we do know is that temperatures are trending warmer for Sunday in the D.C. area.

Daytime highs on Sunday in the D.C. area are forecasted to move into the mid- to upper-40s, some areas to the south nearing 50 degree, perhaps. This is going to be something that we will have to continue to watch.

With warmer temperatures on Sunday, it will obviously take longer for temperatures to drop so that could mean a prolonged period of just plain rain before a switch over to the wintry mess.

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Warming temperatures on Sunday will make forecasting Monday’s storm that much more difficult.

Models are still trying to come into agreement on what exactly we are going to see across the area Monday morning. Some are suggesting rain through the morning rush (with the exception of north and west of D.C. where snow/sleet would fall). Other model data suggests a freezing rain/sleet event across the D.C. region with rain suppressed to the south.

It is just too early to tell as there is going to be a great dichotomy in temperatures across the listening area.

Below is the same computer model run at different times Friday. It depicts what could possibly happen by 7 a.m. Monday morning. The one to the left shows freezing rain across the region while the one to the right shows possibly snow and sleet.

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Below is a completely different model run at two different times Friday. The one on the left shows mainly snow across the region with some sleet to the south while the one on the right shows sleet across the area. Both of these are at 7 a.m. on Monday.

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This is where meteorology comes into play. It is more than just looking at different model runs, it is in-depth forecasting and this is a very tricky forecast.

As the event draws closer, our confidence will improve.

Stay with WTOP for the latest updates about what is known with the weather forecast.